Effect of prostaglandins on uterine contractions in the estrous ewe.

Administration of exogenous prostaglandins at the time of mating may improve fertility via their effects on uterine contractility. The present study was undertaken to compare the effects of three prostaglandins that affect either the male or female reproductive uterine contractility. Contractions in the uterine body of anesthetized ewes during estrus were studied before, during and after a 5 min interval of systemic infusion of prostaglandin F_2α-THAM salt (PGF_2α; 5 mg), prostaglandin E₁ (PGE₁; 5 mg), prostaglandin E₂ (PGE₂; 5 mg) or vehicle. Pressure changes were detected by the use of an open-ended intrauterine catheter and a transducer. Each of the three prostaglandins initially caused a single prolonged contraction that lasted about 10 minutes and had a maximum pressure of 50 mm Hg. Prior to the prolonged contraction, PGE₁ and E₂ caused a relaxation for about 1 minute. In addition, PGE₁ and E₂ caused more secondary contractions (15–20) during the prolonged contraction than did PGF_2α (7–9). The effects of prostaglandin (PG) treatment lasted for 20–30 minutes. The authors conclude that with the dose used the three prostaglandins studied do not have greatly different effects on uterine contractility in estrous ewes.